A fair trial is harder to come by than you might think. A few years ago, we wrote about a paper (ungated version here) by Shamena Anwar, Patrick Bayer, and Randi Hjalmarsson which found that "all-white juries acquit whites more often and are less favorable to black versus white defendants when compared to juries with at least one black member.”

This seems like a relatively hard way for a thief to earn a living, but a 38-year-old New Yorker has been arrested for siphoning off used cooking oil from a pair of restaurants in Connecticut. From the Westport News:

Until two or three years ago, restaurateurs had to pay to get rid of used fry grease. Now they are able to sell it to a few companies in the area, who turn it into bio fuel that can be used to heat houses or operate diesel engines. ...

A new working paper (ungated version) by Jason M. Lindo and Charles F. Stoecker examines the link between military service (in Vietnam) and crime. It has some bad news: "We find that military service increases the probability of incarceration for violent crimes among whites, with point estimates suggesting an impact of 0.27 percentage points." The authors also find offsetting impacts on nonviolent crime and hypothesize that "military service may not change an individual's propensity to commit crime but instead may cause them to commit more-severe crimes involving violence."

A friend of ours had her purse, containing her driver’s license and passport, stolen in a German train station. She reported it to the local police, who told her that she may well get the purse back — minus any cash. Homeless people in the stations troll the trash bins for food and other goodies. When they find purses, wallets, etc., they turn them over to station police. In exchange the police do not roust them out of the stations, which they use for shelter and warmth. In fact, the police were right — the friend did eventually get some of the lost items back.

Philip J. Cook and Christine Piette Durrance have published a working paper called "The Virtuous Tax: Lifesaving and Crime-Prevention Effects of the 1991 Federal Alcohol-Tax Increase." It makes a substantial argument for the upside of higher alcohol taxes:

On January 1, 1991, the federal excise tax on beer doubled, and the tax rates on wine and liquor increased as well. ... We demonstrate that the relative importance of drinking in traffic fatalities is closely tied to per capita alcohol consumption across states. As a result, we expect that the proportional effects of the federal tax increase on traffic fatalities would be positively correlated with per capita consumption.

Encouraging news via the Associated Press: For the first time in almost half a century, homicide has fallen off the list of the nation’s top 15 causes of death. In Mexico, meanwhile, the murder trend continues to move in the opposite direction: During the first nine months of 2011, some 12,903 people were killed in […]

Our latest Freakonomics Radio on Marketplace podcast is called “The Hidden Cost of False Alarms.” (You can download/subscribe at iTunes, get the RSS feed, listen via the media player above, or read the transcript below.)

The central facts: between 94 and 99 percent of burglar-alarm calls turn out to be false alarms, and false alarms make up between 10 and 20 percent of all calls to police.

There are at least three things to consider upon learning these facts:

1. If a particular medical screening had such a high false-positive rate, it would likely be considered worse than worthless; but:

2. With more than 2 million annual burglaries in the U.S., perhaps it's worth putting up with so many false positives in service of the greater deterrent; as long as:

3. The cost of all those false positives are borne by the right people.

A team of mathematicians at UCLA have created an algorithm that can identify with relative accuracy which Los Angeles gang is responsible for an unsolved crime. When tested against cases with a known culprit, the mathematicians could correctly list the gang rivalry involved (out of the three most likely rivalries) about 80 percent of the time. Of these options, they ranked the responsible gang first about 50 percent of the time.

To develop their technique, the mathematicians studied a combination of solved and unsolved gang crimes throughout East L.A. over ten years. Explaining the process, author Andrea Bertozzi, director of applied mathematics at UCLA, says:

If police believe a crime might have been committed by one of seven or eight rival gangs, our method would look at recent historical events in the area and compute probabilities as to which of these gangs are most likely to have committed crime.

The field of forensics has grown by leaps and bounds over the past several years, so much so that decades-old crime cases can sometimes be solved with DNA testing and other modern technology. In an effort to increase case clearance rates (and catch bad guys long gone) police departments have slowly opened more 'cold case' units over the last 20 years; a phenomenon that has been documented and dramatized on TV.

In a new RAND paper, researchers Robert C. Davis, Carl Jensen, and Karin E. Kitchens set out to measure the effectiveness of cold case units by posing a simple question, though one that's rarely asked of police work: What's the return on investment?